Abstract:
The invention concerns a method for reducing the effect of a rough sea ghost reflection in marine seismic data. According to the invention, the method comprises the steps of: providing one or a plurality of pressure sensors sensitive to frequencies below about 1Hz;- using said sensor(s) to receive and acquire pressure data in a frequency band comprised between about 0.03 and about 1Hz; - recording said data; and - processing said data to provide information about the sea-height above the or each sensor. The or each sensor may be a seismic sensor that can acquire seismic data substantially simultaneously with the acquisition of the pressure data in a frequency band between about 0.03 and about 1Hz.
Abstract:
A system and method for generating acoustic source energy in marine seismic operations. A plurality of acoustic energy sources are integrated within seismic streamers (10) to facilitate deployment, power distribution and signal communication. The acoustic energy sources can comprise slotted cylinders (30) activatable with piezoelectric elements (32). By providing an arrray of lightweight, energy efficient acoustic energy sources throughout a seismic receiver array, both zero-offset and far-offset reflection data can be recorded. The acoustic energy discharge can be swept over a time interval, or steered in a selected pattern throughout the arrray, to significantly reduce the impulse energy released into the water. The reflected signals can be compressed back into an impulse for subsequent data processing. Bi-static reflections can be generated simultaneuously with the zero-offset source-receiver locations to improve the vertical and horizontal resolution of data.
Abstract:
The present invention is directed to a hydrophone streamer (100) towable from a marine vessel on a body of water. The hydrophone streamer (100)comprises a plurality of hydrophones (102)electrically connected in parallel. Each hydrophone (102) further comprises a normally-closed pressure activated switch (108) connected in series with a hydrophone sensor (104). Each pressure switch (108) is calibrated to open at a predetermined depth in the body of water thereby disabling the associated sensor (104) without affecting operation of other hydrophones (102) in the streamer (100).
Abstract:
A system for communicating with and powering sensors and cable control and monitoring devices deployed at individual locations along an instrumented underwater cable used in offshore seismic prospecting or scientific, and/or military underwater cable or other applications. The system includes a unique underwater cable architecture, coupler design, and electrical device architecture to improve the reliability of the underwater cable and to allow the electrical devices to receive operational power from the underwater cable.
Abstract:
A floatation device (115), for marine seismic sources. The floatation device includes one or more tubular members, (225) members, and a plurality of couplings for sealing and coupling (235), the tubular members to one another. The couplings include an air valve for filling the tubular members with air. One or more marine seismic sources (205), are preferably coupled to and supported by the floatation streamer cable device.
Abstract:
The invention concerns a module (40) for acquiring geophysical data comprising: at least a case (B''(i), B''), housing processing means including means for digitizing signals; and two cable sections (C''(i)) each comprising: at one first end, a connector (30) designed to be connected to a matching connector; at a second end, a connection piece (140a, 140b) designed to be fixed to the case and provide an electric connection with the processing means housed in the case.
Abstract:
A hydrophone housing (20) includes a hydrophone module or cap (56), which contains a hydrophone. The hydrophone housing (20) clamps around a marine seismic cable (16). The hydrophone housing (20) further includes a first portion (78) and a second portion (82). One of the portions has a receiving recess (86). The hydrophone cap (56) installs on this receiving recess (86). The portions (78, 82) each include a contact surface (94) which contacts the cable (16) when the portions (78, 82) fasten around the cable (16). The portions (78, 82) clamp around the cable (16) via screws (102). The contact surface (94) includes raised bosses (98) which securely grip the cable (16) by increasing contact pressure per unit area in a region of contact between the raised bosses (98) and the cable (16). In another feature, the portion which contains a receiving recess (86) further includes a wire-clearance recess (90) and a wire passageway (106) between the receiving recess (86) and the wire-clearance recess (90).
Abstract:
Depth control apparatus for seismic streamers, comprising a central unit (10) adapted for inserted mounting in the streamer (11, 12) substantially in axial alignement with the streamer, a housing (20) which can rotate about the central unit (10) and carries at least one control wing (7A, B) being angularly adjustable about a transverse axis (7) adapted to be substantially horizontal in operative position, and an electric motor (6) for adjusting the angle of the control wing(s) (7A, B) about the transverse axis (7). The motor (6) is located in the central unit (10) and is adapted to have its current supply (11A) through the streamer (11, 12). The control wing(s) (7A, B) is so arranged on the housing (20) that the transverse axis (7) in operative position runs underneath the central unit (10). A transmission mechanism (6A, 6B, 8, 1, 3A, 3, 13, 13A, 17A, 17) for the angular adjustment of the control wing(s) (7A, B) by means of the motor (6), comprises a slide member (3) which can be moved in the axial direction of the central unit and preferably surrounds the central unit (10).
Abstract:
A method for carrying out marine seismic surveys by using a seismic cable comprising a cable (2) and sensors (4) for detecting seismic signals, said sensors (4) comprising geophone units (6) which rest in the measuring positions on the ocean floor during measurement of the seismic signals and where the seismic cable is moved along the seabed to its next measuring position between the measurements. Before measurements are taken the geophone units (6) are subjected to vibrations so that the geophone units (6) assume a position in good contact with the ocean floor (3) and dig themselves down into it. The invention also comprises a seismic cable for carrying out the method. Here the geophone units (6) are loosely attached within the frame structure (7) and are equipped with at least one vibrator (14) which is powered via the cable (2).
Abstract:
A junction for a towed submarine linear acoustic antenna is composed of successive sections (1, 2). The male part (18) and female part (19) of the connector (7) are suspended and centred by elastic rings (20, 21) so as to absorb the parasitic longitudinal vibrations.